Preparation of compounds by the aid of light.



w. 0. SNELLING.

PREPARATION OF COMPOUNDS BY THE AID OF LIGHT. APPLICATION FILED JULY 1.1913.

1,285,823 Patented Nov. 26, 1918.

i moi i M $1 wvewto c WALTER O. SNELLING, OF PITTSBURGH, PENNSYLVANIA.

PREPARATION OF COMPOUNDS BY THE AID OF LIGHT.

Specification of Letters Patent.

Patented Nov. 26, 1918.

Application filed July 1, 1913. Serial N 0. 776,834.

To all whom it may concern:

Be it known that I, WALTER O. SNELLINo, a citizen of the United States, and a resident of Pittsburgh, county of Allegheny, State of Pennsylvania, have invented certain new and useful Improvements in the Preparation of Compounds by the Aid of Light, of which the following is a description.

My invention relates to improved methods of preparing chemical compositions by reactions which are accelerated by light. Apparatus for practising such methods is described and claimed in my copendmg application, Serial No. 848,355, filed July 1, 1914, which is a continuation of the present application. By my invention many reactions, which are facilitated or induced by the action of light, may be utilized in the formation of highly desirable products. While the effect of light on such reactions has been known in many cases, diliiculties have been experienced in attempting to make use of the phenomenon. Thus in some cases the reaction in the presence of direct sunlight or light from other sources proceeds with violence, or is difiicultly controlled, resulting in the formation of nonuniform products, or products in which the reaction has been carried beyond the desired point. It has been proposed to solve these difficulties in various ways, such as by subjecting the mixture in which a reaction is desired to the action of ultra-violet rays or other specially selected light, or by dilutingthe gaseous mixture of reagents with an inert gas before subjecting it to the action of light. Such methods are successful to only a limited degree or are adapted to special cases only. By my invention a continuous process is provided which may be practised on a commercial scale in a simple and effective manner, and with a large range of applicability. The principle which I utilize is the gradual application of light to reacting bodies, in cases in which light promotes or causes reaction, but does so with harmful or explosive violence if applied fully and directly and without modification. By my invention the amount or efiectiveness of the light upon the reagents during the reaction is automatically regulated and progressively increased from the minimum amount, which is such an amount as may safely be applied to the reagents at the beginning of the reaction, to the maximumv amount, which may be the direct and uninterrupted sunlight, or other form of light, at the end of the reaction. In other words, the brightness or effectiveness of the light in promoting reaction is automatically controlled so as to be at no time stronger than is safe at that time in view of the chemical activity of the reagents at that time.

It seems probable that different molecules of any one of various reagents, such for example as chlorin, show different degrees of activity, some of the molecules in a volume of gas being in a condition readily to combine with hydrocarbons, while other molecules at any given moment are not so ready to combine. In accordance with this view, it may be said that by my invention molecules in the most active condition, in the reacting bodies, are caused to react by the minimum amount of light, and reaction of the less reactive molecules is caused to take place under the action of greater amounts of light.

Accordingly, the objects of my invention are to provide improved methods for preparing various bodies, such as halogen compounds of hydrocarbons, and, generally speaking, whatever bodies may be prepared by the observance of the principles above pointed out, by the gradual and progressive application of light to the mass or mixture of substances, reaction in which is induced or accelerated by light; and to provide apparatus suitable for practising such methods.

Among the various reactions to which my invention may be applied with improved results, the reaction of halogens with hydrocarbons may be particularly noted. It is well known that such reactions are facilitated by the action of light, and proceed with rapidity when the reacting mixture is exposed to sunlight. As indicated above, former methods for utilizing this reaction have shown that the presence of direct sunlight causes such reactions to proceed with such violence as to lead to explosions, and to result in the over-halogenation of the hydrocarbons employed. By my method these difiiculties are avoided. Among the substances which I have halogenized successfully by my improved methods may be mentioned, as examples, natural gas, ethane,

propane, acetylene, etc, all of which may be caused readily to combine with halogens, such as chlorin or bromin, by my method, to form desired compounds Propane, for ex ample, afiords propyl' chlorid as the first a product of chlorination under the described series of plates of glass 1, 2, 3, 4, 5, '6, 7,

conditions. Propyl chlorid is a raw ma= terial from which other useful products containing the propyl group may be readily prepared. In fact, all gaseous, -l1qu1d and vaporizable hydrocarbons, both saturated and unsaturated, are suitable'for treatment in accordance with my process, except a few unsaturated bodies-which form explosive mixtures even in the dark and which are therefore unsuited for direct combination.

In order that a clearer understanding of my invention may be had, attention is hereby directed to the accompanying drawing, forming part of this specification, and illustrating one form of apparatus which may be used in carrying out my improved process. In the drawing, the figure represents in vertical section a cell for carrying out the process.

In the preferred form oftmy invention I make use of a succession of jackets of some transparent material, and introduce the mix ture of halogen and hydrocarbon, or. other vreagents which may be treated in the manner described, within the innermost 'acket, that is, in the jacket farthest remove from the light, where it is protected from the action of light by the outer jackets, through which the light must pass before it can reach the mixture in the inner jacket. From this point the mixed substances are caused to traverse each jacket in turn, from .the inner to the outermost, the halogenation or ther reaction proceeding inincreasing degree as the reacting mixture is exposed to increasing amounts of light.

In practical use I may employ the apparatus shown in the drawing, in which a 8, 9, 10, are set in parallel position, alternate plates, 3, 5, 7, and 9, being secured in any suitable manner at o'ne end,' as the bottom, to frame member 11 of the cell, these plates terminating at their other or topends some distance from frame member 12. Alternate plates 2, 4, 6, and 8 are secured ,at the opposite end to frame member 12, and do not quite extend to frame member 11, Plates 1 and 10, constituting the front and back of the cell, extend from one frame member to I the other. Reacting gases or ingredients, as

for example chlorin and a hydrocarbon such as acetylene or as propane, are admitted into the apparatus to the rear of plate 9, by inlet 13, and the chlorinated hydrocarbon, or other completed product, is removed through outlet '14, immediately to the rear. of front plate 1. The particular point however at which the condensed chlorinated product is removed will 'of' course depend upon' its condensability, that is the temperature at which it becomes liquid, and the temperature maintained in the apparatus. The apparatus is of course provided with clese-d. sides, not shown), so'that the path of the reacting ingr dients frem the inlet te the eutlet 14 is, as shown by the arrows, around the various plates in order, from the back to the front. I usually employ a mirror as the last plate, 10, in the apparatus, which seems to produce beneficial results, but this is not necessary. The source of light in the drawing is represented at 15, in front of the first plate 1. This light may be sunlight, or other source of light. If an artificial light is used a reflector 16, back of the same, would be used, as shown.

It isevident that the form of apparatus and process just described does not depend upon the nature of the transparent material used, since I may make use of plates of quartz, celluloid, mica, or other material through which light may be transmitted. Furthermore, m invention 18 not limited to havebeen used successfullyby me, the reacting mixture being introducedjnto the rear member, farthest from the light, and

caused to travel in order through each tube of the set, finally passing through the front or outermost tube, ex osed to the dire :t presence of the light. r'a continuous spiral member may be used, in wni h the light i caused to pass through theouter turns of the spiral to reach the inner turns, the mixture being introduced at the center, and the light being supplied, if desired, from opposite sides.

Where plates of glass are used, I find that by setting them close together they act to perform the well-knownunction of'a wire gauze to reduce the po's'sibilitv of explosion, in addition to their effect of progressively decreasing the light supply to the rear elements of the cell. This effect is not however,

.essential to my process, which may be practised with the transparent elements set too far apart to act in this manner.

In many cases the ,reactin themselves in the front part' of t e apparatus substances have considerable effect in shutting off the the chlorination of the gas and'theplates of glass; take upthe of p the spacing thereof, or the light-conductivity 11ght from the rear part of the cell: Thus in l V a hydrocarbon, the chlorin is somewhat yel ow in color, and both ates of transparent material,by altering thereof.- In the case of a chlorination process with transparent glass plates, I find that but little light gets through six plates with intervening chlorin. A greater number of plates may be used however, where the conditions make it desirable. The plates in the apparatus shown may be readily adjusted or clamped in position and readily removed.

It will be noted that in the described apparatus the light and the reacting mixture travel against each other. This insures that at the point where the light has its maxiform, regular and nonviolent action; to a smooth and desirable typeof'halogenation;

The presence of chlorin in increasing proportions in the path of the actinic light insures a progressive cutting down of the actinic rays which are capable of aflecting chlorin. In other words, where the tendency to reaction is the greatest the catalytic effect of the light is the least, and vice versa.

If desired, some of the plates or other media used may be colored to cut off all space beyond the same from the influence of a certain color of light, or to modify or reduce the light transmitted through some or all of the plates. Thus if it be found desirable to perform a part or all of a given reaction under the action of rays from any part of the spectrum, the apparatus may be readily adapted to the purpose. Similarly various sources of light, which should be approximately constant for best results, may be used, sunlight, however, being best for most purposes.

The process. may be carried out with a mixture of reagents in any form sufliciently light-conductive, not to prevent the transmission of light through the same to the rear elements of the cell, and which reagents are acted upon by light in the desired manner. If liquids are used, the same may be caused in any suitable manner to flow through the apparatus. If it is desired to use a liquid in vaporous form, the cells may be sufliciently warmed, or the liquid or a solid may first be vaporized. The process is useful for treating substances whose boiling points are not so high that the heat necessary to vaporize the same will cause excessive reaction between the mixed ingredients in the cell, or a reaction proportional to that caused by the light. The reaction achieved by my process may of course be readily con- 5% trolled and caused to proceed to any desired extent by suitable alteration of the elements of the apparatus used, as described above.

Since the penetration of actinic rays through any gaseous mixture is inversely proportional to the concentration in such mixture of any material affected by such rays, it will be obvious that in the present simple method of causing the light to shine through an advancing column or body of vapor or gases affected by it, an automatic regulation of the amount of reaction taking place at any given point in the advance is made possible. Taking a mixture of chlorin and methane, for example, and advancing it against the travel of the light it will be obvious that at the point where the light first impinges and its actinic power is at a maximum the concentration of the chlorin and of the methane will be at a minimum while at the point of maximum concentration of these two gases the reaction-inducing power ofthe light will be at a minimum. At any intermediate point the concentration and intensity will beintermediate. "This results in" products. This is very desirable in many arts; as in chlorinating hydrocarbons.

My process as described may be carried out continuously and in an easily regulable and flexible manner by means of the apparatus described, and this I consider a desirable form of apparatus for my invention, but it is obvious that, in its broadest sense, it is not limited to the use of the same, but may be practised, broadly, by the use of any means which permits the amount or chemical activity of light used in, the process to be proportioned at each stage of the process to what is necessary and suitable at that stage. Generally speaking this means that the light efiective throughout a desired reaction shall be so regulated, obscured, or screened as to gradually and progressively increase in activity from the beginning of the process to the end. Thus the invention may be carried out, with many of the advantages of the preferred method, by progressing the substances in which reaction is desired past a source of light, first through or behind a relatively opaque medium, and thence through or behind media of progressively increasing transparency, all of which are subjected to the uninterrupted action of the light. Or the process may be carried out by exposing the substances in a container to a source of light, between which and the container a series of light-screens or obscuring means are interposed, and progressively and gradually removing the same into nonobscuring position.

Having now described my invention what I claim and desire to protect by Letters Patwhich reaches the said substances at the beginning of their passage passes throu several thicknesses of, said conduit and contents, and the light which reaches said substances further along passes by a shorter path through said conduit and contents to reach said substances.

2. The rocess of reparing halogen com pounds 0 hydrocarbons, whlch consists in mixing a halogen and a' hydrocarbon in suitable proportions, and progressing the same continuously toward a source of light in a path crossing the path of light from said source a plurality of times.

3. The process of chlorinating parafin hydrocarbons which comprises fproducing a mixture of chlorin and a para 11 hydrocarbon, illuminating such mixture by actinic light, and causing said mixture to flowtoward the source of such light in a path crossmaasaa I ing the path of such light a plurality of tnnes= 4. The process of chlormating organic compounds which comprises passing actinic light through a gaseous layer comprising chlorm in a transparent compartment, so as to modify the chemical activity of the light.

c This specification signed and witnessed 35 this 23rd day of June, 1913.

WALTER Witnesses:

C. R; KERR,. A. J. Pmnmrs.

o. SNELLING. 

